1. Field of the Invention
This invention relates to a chain structure which may be used in conjunction with a freewheeling mechanism of a bicycle or like vehicle. In particular, this invention pertains to a chain structure which includes a base plate having cylinder members extending therefrom for coupling to a connecting plate having elliptically contoured openings formed therethrough to provide a secure coupling between the cylinder members and the connecting plate.
2. Prior Art
Freewheeling chains of prior art devices are generally formed by a series of links coupled to each other by connecting plates which form a structure for rotating the wheels through a mechanism which allows for changing the gear ratios. Thus, the connecting plates must have sufficient structural integrity to couple the links, otherwise the chain may snap and possibly lodge itself in the gap between the freewheeling mechanism and the spokes.
A prior art structure is shown in FIGS. 7 and 8, which includes a connecting plate A having a pair of apertures A1 formed therethrough at respective ends. A base plate B is provided having a pair of integral cylinders B1 at respective ends and in alignment with respective apertures A1. Each aperture A1 includes an overlapping large circular opening A11 and a small circular opening A12 near an outer portion of the connecting plate A. Each cylinder B1 has an annularly formed groove B11 at an upper section and a knob formed at a respective extremity. The annular grooves B11 has a diameter substantially equal to the diameter of the small circular aperture or opening A12, while the diameter of the large circular aperture or opening A11 is slightly larger than the outside diameter of the knob so that the cylinder B1 may be inserted into the aperture A11 until the annular groove B11 is within the large circular aperture A11. The base plate B is pulled toward the small circular aperture A12 until they snap together and the chain structure is formed.
However, the width of the annular groove B11 is larger than the thickness of the circular apertures A11 and A12 which increases wear. The other shortcoming of the prior art is that the chain will skip or jump during pedalling or possibly jump from the chain wheel.